1. Technical Field
The present invention relates to a technique for ejecting liquid such as ink.
2. Related Art
A liquid ejecting technique for ejecting liquid (for example, ink) of a pressure chamber from a nozzle by changing the pressure of a pressure chamber using a pressure generating element such as a piezoelectric element or a heating element has previously been proposed. An ink jet type recording head employing such a technique is provided with a plurality of pressure chambers communicating with a nozzle, a reservoir which is a common liquid chamber communicating with each pressure chamber, and a pressure generating unit that changes the pressure of a pressure chamber and thereby ejecting liquid from a nozzle. As the pressure generating unit, for example, an axial vibration type piezoelectric element, a flexible vibration type piezoelectric element, an element using electrostatic force, a heating element, and the like are employed.
In ink jet type recording heads, ink in the nozzles which is not used for printing for a long time is thickened and there are problems in that the ejecting amount is reduced at the time of the next ejection and in that the thickened component of the ink (below referred to as “thickened component”) becomes clogged in the nozzle. Here, a configuration is employed in which a flushing operation of ejecting the thickened component from the nozzle is performed periodically (for example, JP-A-2000-117993 and JP-A-2003-001857).
In addition, in the ink jet type recording head, micro-vibration driving is performed to micro-vibrate the free surface (meniscus) of the ink exposed to the inside of the nozzle to an extent at which the ink is not ejected. By agitating the ink in the vicinity of the nozzle by micro-vibration driving, it is possible to maintain the ink in the vicinity of the nozzle at an appropriate viscosity.
However, in a case where micro-vibration driving is performed, since the thickened component in the vicinity of the nozzle is diffused inside the pressure chamber, it is necessary to also discharge the thickened component diffused not only in the vicinity of the nozzle but also up to the inside of the pressure chamber in order to restore the desired ejection characteristic with a flushing operation after performing the micro-vibration driving. That is, as a result of the micro-vibration driving, there is a problem in that the necessary ink ejection amount is increased in the flushing operation.